It is known that herbicidal compositions containing cyclohexanedione oxime compounds such as clethodim, sethoxydim, alloxydim, cycloxydim, butroxydim, tralkoxydim, tepraloxydim, and profoxydim are difficult to formulate, since the active ingredients are sensitive to chemical instability. Many adjuvant materials, surfactants, and even water, for example, can lead to significant chemical degradation. Because chemical stability is commercially desirable, as well as required by the Environmental Protection Agency, it is common in the agricultural chemical industry to formulate cyclohexanedione oxime compounds with an emphasis on chemical stability and good mixing characteristics, rather than on optimization of herbicidal efficacy.
Current graminicides typically require the addition of oil-based adjuvants (known as “crop oil concentrates”) in order to achieve commercially acceptable stability and weed control. In particular, herbicidal efficacy for cyclohexanedione oxime compounds requires adding crop oil concentrates at the time of application in the grower fields. Rather than having to prepare a tank mix from separate herbicide and crop oil containers, it would be commercially desirable to prepare herbicides and crop oils in one formulation which is ready to dilute. However, because crop oil concentrates commonly used in the marketplace are recommended at the use rate of 16 to 32 fluid ounces per acre, it has not been practical to provide cyclohexanedione oxime compounds and crop oil concentrates as premixed, ready to dilute formulations.
Ready to dilute adjuvant-containing post-emergent herbicidal formulations are described in U.S. Pat. No. 5,084,087. The formulation comprises a mixture of one or more herbicidal compounds, a polyoxyalkylene nonionic surfactant having a hydrophilic-lipophilic balance (HLB) of from 10 to about 14, an anionic surfactant selected from the group consisting of the dialkyl metal sulfosuccinates and the metal alkylbenzene sulfonates, optionally a low foaming polyoxyalkylene nonionic surfactant having an HLB of less than 10, and a lower alkanol ester of a long chain fatty acid. This patent does not describe or suggest the particular herbicidal composition of the present invention, including the surfactant component and advantageous properties described herein.